The MRC/BHF Heart Protection Study is much the largest trial in the
world of cholesterol-lowering therapy and of antioxidant vitamin
supplementation in people at increased risk of heart disease.

Substantial uncertainty had existed about the long-term benefits of
cholesterol-lowering drug therapy for particular types of patient,
and the extent of its use is limited. Uncertainty as to the possible
benefits, or risks, of antioxidant vitamin supplementation was even greater.

To help resolve these uncertainties, the MRC/BHF Heart
Protection Study was designed to be really large, to involve a
substantial reduction in blood LDL cholesterol levels and a substantial
increase in antioxidant vitamin levels, and to include
a wide range of patients at substantial risk of death from heart
disease and other causes.

Between July 1994 and May 1997, 20,536 individuals were recruited
in 69 hospitals from within various prior disease categories (coronary
disease, other occlusive arterial disease, diabetes, hypertension) and
other categories (women, the elderly, those with average or below average
cholesterol levels) where there was uncertainty
as to how worthwhile, and safe, are these treatments.

Half of the participants were randomly allocated to receive 40 mg
daily simvastatin to lower blood cholesterol levels, and half to
receive dummy "placebo" tablets. In addition, within each of these
two groups (using a "factorial" design), half were allocated to
receive antioxidant vitamins (600 mg E, 250 mg C and 20 mg beta-carotene
daily), and half to receive placebo capsules.

Compliance with the study treatments was good, resulting
in large average reductions
in blood levels of total cholesterol (1.2 mmol/l)
and LDL cholesterol (1.0 mmol/l),
and large increases in antioxidant vitamin levels.
During the
scheduled treatment period, there were approximately 4500
major vascular events (which included 2000 coronary events and
1000 strokes) and 3000 deaths (1500 from vascular causes
and 1500 from other causes).

Consequently, the MRC/BHF Heart Protection Study provides
reliable evidence about the effects of these cholesterol-lowering
treatments and antioxidant vitamin supplements on
mortality and major morbidity in a wide range of circumstances.